The TT RS is, by far, the fastest and most powerful evolution of the current-generation TT. It was developed by Audi Sport, meaning it benefits from the same genes as the R8 and the RS 3. It sits at the top of the TT line-up, and it's only offered as a coupe.

What Makes it Tick?Power for the TT RS comes from a turbocharged 2.5-liter TFSI five-cylinder engine that makes 400 horsepower from 5,850 to 7,000 rpm and 354 horsepower between 1,700 and 5,850 rpm. When the torque drops off, the horsepower picks up.

The five-cylinder is backed up by a seven-speed dual-clutch automatic transmission can you can leave in drive or shift manually using paddles. It channels the engine's power to the four wheels via Audi's quattro all-wheel drive system.

Power is high, but weight is relatively low at just 3,300 pounds. The TT RS hits 60 mph from a stop in 3.6 seconds and it goes on to a top speed of 155 mph. Buyers planning on hitting the track can pay to get the limiter raised to 174 mph.

Fuel economy checks in at a surprisingly high 19 mpg in the city, 29 mpg on the highway, and 22 mpg in a combined cycle. The five-cylinder requires premium fuel, however.

Spotter's GuideYou can tell by the RS apart from a standard TT by looking at its front end. It get a model-specific grille with a "quattro" emblem on the bottom part, a redesigned lower bumper that incorporates sizable air vents, and, of course, a TT RS emblem.

Out back, you'll notice oval exhaust tips on either side of an air diffuser and a large spoiler on the trunk lid. The RS also sits on five-spoke, 19-inch alloy wheels.

The changes continue inside, where Audi Sport added a flat-bottomed steering wheel, carbon fiber-look inlays made out of aluminum, and sport seats for the front passengers.

There are several standalone options, including real carbon fiber trim in the cabin, 20-inch alloy wheels, red brake calipers, a more discreet spoiler that extends from the hatch, and a sport exhaust system.

Key CompetitorsWith 400 horsepower and a relatively reasonable price tag, the TT RS doesn't have very many direct competitors. Buyers can also look at the mid-engined Porsche 718 Cayman S, which is down on power but more expensive, and the BMW M2, which is down on power but less expensive.